Digital television, popularly referred to as DTV, is an enhanced television system capable of transmitting and receiving digitized signals, displaying digital images and playing digital audio. While some of these features may be present in current analog television systems such as the national television standards committee (NTSC) system, the sequential couleur avec memoire (SECAM) system and the phase alternate line (PAL) system, the combination of digitized transmission, reception, video and audio distinguishes digital television from current analog television systems.
Digital television employs various digital signal processing techniques and utilizes scarce bandwidth in a more spectrally efficient manner to transport and present audio and video signals in a way that is superior to current analog television systems. In this regard, digital television allows more channels containing more information to be broadcasted within an equivalent bandwidth utilized by current analog television systems. Accordingly, any excess bandwidth can be re-allocated for use by other types of communication systems. Broadcasters utilizing digital television systems are therefore, capable of providing over-the air television signals containing higher picture resolutions than current analog broadcast television systems
In conventional HDTV applications, a single processor may be utilized for processing a plurality of audio and video tasks. Each of the plurality of audio and/or video tasks may utilize real deadlines for completing the processing of the tasks. For example, a digital signal processor (DSP) may be utilized to process a plurality of audio bitstream tasks for an audio processing application. Each audio bitstream task may have strict real time requirements for completing the corresponding processing task. Some conventional HDTV applications may not utilize task scheduling and, as a result, one or more audio bitstream processing tasks may be processed later than their corresponding real time completion deadlines. In such circumstances, the decoded audio stream may become de-synchronized which may significantly reduce the quality of the decoded audio stream. Most conventional HDTV applications utilize task scheduling with pre-emption in circumstances where a single processor has to process more than one task simultaneously. However, during preemptive processing of multiple tasks, the DSP frequently has to buffer large portions of data between executions of different tasks. Task scheduling with preemption may, therefore, be an undesirable method for scheduling multiple processing tasks as it increases memory use and reduces overall processing efficiency. In digital television (DTV) systems, for example, such scheduling may adversely affect audio and/or video quality.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.